Feancis b



NTTED STATEs PATENT OFFICE.

" EnANois E. srrEvENs,

or NEW YORK, N. v.

IMPROVEMENTJN VALVES Foa STEAM-ENGINES.

specification forming pari of Letters Patent No.aooo, dated Novembre 3, 1st-3.

T0 all whom t may concern.'

. granted to me on the lst day of July, A. D.

1862, and numbered 35,788, a valve is described at Figures VIIIa-nd IX, by which the steam can be discharged from the cylinder of a double'eduction steam-engine by the iirst eduction, providing that this valve communicates with a'passageway made midway in the length of the cylinder; and asthe valves discharging the steam by the first eduction may have the pressure alternately in opposite directions, this valve is shown to he retained on its seat by maintaining a constant pressure on its top by steam led from the boiler.

The object of my invention is to improve this valve by dispensing with the action ot' the steam from the boiler vto keep it on its seat, and by substituting instead two seats, so that when there is a plenum in the cylinder the valve may bear against one seat., and when thereis a vacuum in the cylinder the valve may bear against the opposite seat, the openings 6, 7, and 8 being placed on one seat and communicating with the opening D placed on the opposite seat.

.FigrI is a fullsized longitudinal section of the valve and the two seats.

A is one seat, and B is the other seat, with its face placed parallel to the face ot A.

' C is a valve, the throw or motion of which is five inches-the same as in valve referred to. It is not necessary that thisva-lve be so tted that its two faces shall be vin contact with the faces of the seats A and B at'the same time, as a small amountl of playl is ad missible. The openings 6, 7, 8, and 9 are the same asin the valve above referredto, but the openings 10 and 11 are omitted in the seat A, and instead the opening D is placedin the ofthe openingD must equal the aggregate width ot the openings in the seat A,and the width ot' the bridgesE F between the openings of the seat A must be a little greater than the opening D. rIhis valve can be simplified by making but one opening in the lower seat,

yas well as in the upper seat, as in the fullsized longitudinal section shownin Fig'. II,

where F is the lower seat, G the upper seat, H the valve, and I the opening in the lowerV seat, made equal in width to `one of the open- .ings 6,7, or 8, and K. the opening in the upper seat, the throw being ve inches. as in Figa I. Here, although 'the time at which the valve commences to open and at which it closes will bethe same as in Fig. I, theopening will be only one-third as great as in Fig.

I; and it' the opening in both seats is made as large as D, and if the time at which the valve commences to open and to close is the same asin Fig. I, then thev valve would require a motion or throw of fifteen inches,.instead of l livel inches', because the. opening D would be three times the opening of I.

What I claim as my invention is'- 1. Aslide-valve connected with a passage made midway in the length ot' a cylinder and made to bear alternately with its opposite faces against two seats, as herein set forth and described.

2. In connection with my tir'st claim, placing a greater number of openings in one seat than in the other, as a means ot' diminishing the throw ofthe valve without decreasing the size of thepassage-way, as herein set forth and described. v

Dated June 8, 1863.

' FRANCIS B. STEVENS. Witnesses:

ALBERT S. EAsUM, Tuo. SADLER. 

